Abstract

To study the absorption of baicalin (BA), baicalin-phospholipid complex (BA-PC), and two kinds of self-microemulsifying drug delivery system (SMEDDS) of BA-PC (BA-PC-NE-SMEDDS with natural emulsifier and BA-PC-NS-SMEDDS with nonionic surfactants) and predict the ability of improving bioavailability through changing the formulation of BA. Transmembrane transports of each formulation were studied by Caco-2 cell model and the concentration of BA was determined by HPLC. With the increasing concentration of BA, the transport rate and apparent permeability coefficient (Papp) of BA was increased,indicating the passive absorption mechanism of BA. While with the increase of transport time, the transport rate and Papp of BA was decreased slowly, most likely due to the biological transformation of BA during the permeation process as reported in other people's paper. When coupled with P-gp inhibitor (Verapamil), the efflux rate (ER) of BA decreased from 2.07 to 0.48, indicating it was the substrate of P-gp. Compared with BA,the cumulative permeate quantity of BA-PC and BA-PC-SMEDDS were with no significant increase before 90 min (P > 0.05), but increased obviously after 90 min (P < 0.05). Three hours later, the cumulative permeate quantity and Papp showed significant differences (P < 0.05) among each formulation and were arranged in the following order: BA-PC-NS-SMEDDS > BA-PC-NE-SMEDDS > BA-PC > BA. Furthermore, the Papp of BA-PC and BA-PC-SMEDDS was significantly greater than that of BA coupled with Verapamil (P < 0.05). PC promotes the permeation of BA; PC-SMEDDS further accelerates its permeation bases on BA-PC; And BA-PC-NS-SMEDDS shows the better effect than BA-PC-NE-SMEDDS to promote the permeation of BA.